What diagnostic tests should be ordered for a 35-year-old female with Systemic Lupus Erythematosus (SLE) on corticosteroids and Hydroxychloroquine, presenting with lower limb weakness, urinary incontinence, and paraplegia with absence of deep tendon reflexes?

Diagnostic Approach for SLE Patient with Paraplegia and Urinary Incontinence

Lumbar puncture and spinal cord MRI (option C) is the most appropriate diagnostic approach for this patient presenting with paraplegia, absent deep tendon reflexes, and urinary incontinence.

Clinical Presentation Analysis

The patient presents with a classic triad suggesting spinal cord involvement:

• Lower limb weakness progressing to paraplegia
• Absent deep tendon reflexes
• Urinary incontinence

This constellation of symptoms in a patient with SLE strongly suggests myelopathy, which requires urgent evaluation and treatment to prevent permanent neurological damage.

Diagnostic Reasoning

Why Spinal Cord MRI is Essential

• SLE myelopathy presents as rapidly evolving transverse myelitis or ischemic/thrombotic myelopathy 1
• Contrast-enhanced spinal cord MRI is recommended to:
  • Exclude cord compression
  • Detect T2-weighted hyperintense lesions (present in 70-93% of cases)
  • Assess the extent of spinal cord involvement 1
• The absence of deep tendon reflexes with paraplegia suggests lower motor neuron involvement, which is consistent with spinal cord gray matter dysfunction 1

Why Lumbar Puncture is Necessary

• CSF analysis is crucial to:
  • Exclude infectious causes of myelitis
  • Assess for inflammatory markers
  • Rule out other neurological conditions 1
• Mild-to-moderate CSF abnormalities are common (50-70%) in SLE myelopathy 1

Why Other Options Are Less Appropriate

Option A (LP and CT brain)

• CT brain lacks sensitivity for detecting subtle neurological changes in SLE
• The clinical presentation points to spinal cord rather than brain involvement

Option B (LP and MRI brain)

• While MRI brain is superior to CT, the patient's symptoms (paraplegia, urinary incontinence, absent DTRs) strongly indicate spinal cord pathology
• Brain imaging would be appropriate if there were symptoms of cerebral involvement (confusion, headache, seizures)

Option D (LP, MRI and MRA brain)

• MRA brain would be more appropriate if there were signs of cerebrovascular disease
• The clinical presentation does not suggest cerebrovascular involvement

Management Implications

Early diagnosis is critical as delay in treatment is associated with poor outcomes. The EULAR guidelines recommend:

• Prompt initiation of high-dose glucocorticoids (intravenous methylprednisolone) followed by intravenous cyclophosphamide for SLE myelitis 1
• Treatment should be initiated as soon as possible, ideally within the first few hours after diagnosis 1
• Maintenance immunosuppressive therapy is needed to prevent relapses, which are common (50-60%) 1

Prognostic Factors

Poor prognostic factors for SLE myelopathy include:

• Extensive spinal cord MRI lesions
• Reduced muscle strength or sphincter dysfunction at presentation (already present in this case)
• Presence of antiphospholipid antibodies
• Delay (>2 weeks) in the initiation of therapy 1

Early diagnosis with appropriate imaging (spinal cord MRI) and CSF analysis (lumbar puncture) is therefore crucial for this patient's outcome.